This invention is directed at significantly accelerating the rate of reaction and increasing the accuracy of making a qualitative and/or quantitative determination involving a biological or other fluid containing cells. More particularly, the invention is directed to a method and apparatus for accelerating the rate of an immunological reaction in which microspheres coated with at least one selected antibody are rapidly mixed with a sample containing the cells without significantly impairing the cellular properties of interest. The invention also can be useful in certain biochemical reaction determinations.
Immunological reactions of the type with which this invention is concerned include antigen/antibody reactions in which a microsphere, either magnetic or non-magnetic in character, is coated with the antibody, for instance, which will bind specifically with the antigen on a cell surface for making the desired determination. Such a reaction may include tagging or labelling the antigen for specific binding or can include labelling or tagging of a cell with respect to an antigen within the cell.
In the past, laboratory practice involving such mixing of labelled or tagged microspheres in a sample containing the cells involved incubations from several minutes to several hours. One reason for such extended periods of time is attributable to the differences among the physical and chemical properties in the population of available microspheres for coating with the selected tag or label. Such extended time periods greatly restrict such procedures and prevent any type of rapid assay and particularly application to automated techniques.
The prior art has attempted to optimize the time period of specific reactions by varying the volume and concentration of reactants together with the temperature at which the reaction is conducted and the desired mixing. Clearly, there are lower limits on how small a volume of the reaction mixture can be utilized. Further, increasing the temperature can denature the immunological reactants and strenuous mixing also can damage the cells.
Various types of mixing systems and methods also have bee utilized in the prior art for particular immunological reactions. The prior art suggests agitating the mixture for extended periods of time which are undesirable for automated systems. Such automated systems are designed specifically for analyzing large numbers of samples per unit of time.
The method and apparatus embodying the invention successfully achieves optimum results in such immunological reactions by means of increased reaction rates which are unexpected and unusual in this field. Further, the invention enables a continuous mixing procedure which is especially conducive to automated systems. Further, the invention can be applied to accelerating mixing of reactants and formed bodies, such as bacteria, viruses and fungi which have specific properties of interest derived from biochemical reactions.